Review of magnetic properties of Fe-Ni alloys

During the past two decades, improved understanding of the fundamental magnetic behavior of Fe-Ni alloys has made them one of the most versatile class of soft magnetic materials. No longer is the concern limited to high permeability and low coercfve force at room temperature. Alloys have now been custom-crafted to meet high permeability requirements at cryogenic temperatures, exhibit a skewed hysteresis loop for pulse transformer use, or a square hysteresis loop combined with stress insensitivity and controlled coercive force for memory applications. These examples are discussed in terms of the relationship of magnetic properties to structure and composition in Fe-Ni alloys.